The invention relates to improvements in digester vessels, also known as autoclaves, for processing material to be converted under high temperatures and high pressures, and particularly under pulsating pressures. More particularly, the type of digesters which are improved by the features of the present invention are those used in the chemical industry which must carry out converions of material under conditions of increased temperatures and pressures with operational safety.
An example of the type of vessel is those which are provided with a protective lining, such as those which have special demands as, for example, core reactors which require an unusually high degree of safety of operation.
In a digester or processing vessel of this type, it is necessary to protect against simultaneously occurring different types of stresses or demands, for example, those created by heat, pressure, corrosion, radiation and like processing conditions which must be contained within the vessel and not be permitted to damage the vessel or which must be contained completely within the vessel so as not to permit the contents or processing conditions to become exposed to surrounding machinery or personnel.
An example of such a processing vessel is shown in U.S. Pat. No. 3,494,829 which shows in the drawing of FIG. 1, an outer radiation protective sleeve and an inner layer serving as a heat reflector.
An object of the present invention is to provide a digester vessel which is adapted to have features capable of material processing under high temperatures and pressures wherein the application of pulsating pressures may occur as well as the presence of hot hydrogen gases and other similar reaction mediums.
An example of such a case is where a processing vessel is used as a reactor for the direct gasification of coal by means of hydrogen with pulsating pressures which vary between 0 and 100 kp/cm.sup.2 and at temperatures of 1,000.degree. C.
In these requirements, the following critical demands are presented at the same time, pulsating pressure; high temperature; and aggressiveness of the hydrogen medium.
A feature of the invention which is utilized in accommodating the demands in this type of reaction is to provide an inner layer formed of a corrugated tube, with an intermediate layer, and an outer wall that has a pressure relieving opening extending therethrough.
The construction of the inner hollow body or wall as a corrugated tube is particularly advantageous in being able to compensate for longitudinal expansion because of temperature effects without resulting in strains causing local deformations of the inner wall. This construction in acccordance with the invention is useful because of specific materials used which are resistant to high temperature are by nature very brittle and, therefore, are sensitive to strains caused by expansion. Also, the arrangement is provided to permit the release of reaction gas which builds up between the walls.
In one form of the invention, the corrugated tube has a contour which is helically shaped so that it can be installed by rotating and threading the inner wall into the surrounding intermediate layer.
In further accordance with the invention, there is an intermediate layer provided between the inner and outer walls. The intermediate layer has expansion and slip joints which accommodate relative movement in a radial as well as an axial direction and the intermediate layer serves as a support for the inner wall. In processing the material within the chamber within the inner wall, the intermediate layer compensates for temperature gradients of on the order of 100.degree. C. In addition to compensating for these temperature gradients, the intermediate layer must provide a medium which transfers uniformly the radial or axial forces. It is further contemplated that the structure incorporates mold bodies which are shaped to fit the corrugated outer surface of the inner wall and also the intermediate layer. These mold bodies permit relative axial radial and circumferential movements between the corrugated wall and the intermediate layer. The mold bodies are provided with a loose fit and have cylindrical outwardly facing surface which is of particular advantage in mating with the smooth cylindrical surface of the intermediate layer and the structure also provides advantages in the equalization of expansion and provides advantages in technical finishing of the assembly.
A further feature of the invention is provided in construction of the inner corrugated tube with an end closure and a radial flange of corrosion and temperature resistant material which is secured to the inner wall and is welded to the outer wall. This structure prevents hot hydrogen gas under pressure from reaching the areas between the layers and avoids the difficulties which are caused by such an occurrence. The annular flange or disk at the end of the tubular inner wall has grooves or annular shaped corrugations and deformations which generally extend in the form of concentric grooves. These grooves in the end flange compensate for and prevent strains and stresses and deformation in the material of the flange.
An object of the invention is to provide improved material processing vessel which is particularly well suited for the gasification of coal with hydrogen at pulsating pressures which range between 0 and 100 kp/cm.sub.2 and temperatures of 1,000.degree. C.
Other objects, advantages and features as well as equivalent structures which will become more apparent with the disclosure and teaching of the principles of the invention in connection with the specification, claims, and drawings, in which: